One of the main advantages of using Leaflet to display IIIF manifests is that you can switch between a map and an IIIF manifest with some ease. In other words Leaflet can be used to show the location of geo-tagged images and provide an interface in which you can pan & zoom around these very same images. You can get a better idea by looking at this demo map of Dublin 1916.

This map uses a number of postcards created after the 1916 Rising in Dublin. These postcards are held by the UCD Digital Library. The map shows the location depicted in each of the images. If you click on a marker then you can view the postcard selected and pan & zoom around the image.

Switching between a basemap map layer and an IIIF manifest is not as straightforward as you might think. The reason for this is that the map and the IIIF manifest use different map projections. Therefore you need to change the map projection every time you switch between a manifest and the map.